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Aortic Valve Stenosis: Difference between revisions
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|<0.60cm<sup>2</sup>/m<sup>2</sup> | |<0.60cm<sup>2</sup>/m<sup>2</sup> | ||
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|[[Image:AoScw03.jpg|350px]] | |||
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!Serious AoS: PG max 101mmHg, PG mean 69mmHg<cite>1</cite> | |||
!PHT moderate Aol <cite>1</cite> | |||
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|colspan="2"|Click [http://www.csecho.ca/cardiomath/?eqnHD=echo&eqnDisp=avavti '''here'''] to calculate AGM | |||
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==Aortic valve area (AVA)== | |||
For the calculation of the aortic valve surface, the continuity equation can be applied. | |||
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|colspan="2"|Continuity equation: | |||
A1.v1 = A2.v2 | |||
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|[[Image:Continuiteitsvergelijking.png|350px]] | |||
|Where: A=area (∏r<sup>2</sup>) cm<sup>2</sup> | |||
v=velocity, cm/s (can be used as maximum speed or TVI) | |||
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|colspan="2"|so : | |||
Aortic valve area (AVA)=( D LVOT/2 )<sup>2</sup> x 3:14 x Vmax LVOT/Vmax peak in AoS jet | |||
Where: D LVOT=diameter LVOT in cm | |||
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==Dimensionless index (DI)== | |||
If you are unable to get a good measurement of the LVOT can also the ratio of the velocity in the LVOT and the speed of the aortic valve to give a good impression about the severity of aortic stenosis . | |||
DI = V LVOT/V aorta | |||
In a DI = 25, there is almost always a severe aortic valve stenosis . | |||
==Low- gradient aortic stenosis vs . pseudo stenosis== | |||
In an aortic valve stenosis with a low gradient (<30 mmHg ), and poor left ventricular function is to be a valve surface calculated . If an AVA <1 cm ² is calculated can be a severe aortic valve stenosis are present despite the low gradient . However, it could also be that the valve does not open properly due to low cardiac output ( pseudo stenosis ) . To gain more insight into the aortic valve or a "true " or stenosis has a "pseudo stenosis " seems dobutamine stress worthwhile . If during dobutamine infusion up to 20 micrograms / kg there is an increase of more than 20 % in the LVOT VTI (ie cardiac output ) and the calculated valve area remains below 1 cm ² then there is a true aortic stenosis . If not , and there appears to be a contractile reserve (which is predictive of a better prognosis after aortic valve replacement ) it is called a pseudo stenosis. | |||
==References== | |||
<biblio> | |||
#1 pmid=19065003 | |||
</biblio> | |||